The Science Behind Tattoos

Tattoos have been around for thousands of years, since about 12,000 BC. It’s unclear how people first started tattooing themselves and others, but what is clear is that they didn’t quite know why the tattoos stuck; that is, why their skin didn’t heal them like they do normal scars.

In fact, we didn’t learn why tattoos work until the 20th century, which is just a drop of water in the history of body ink. Tattoo needles penetrate deep into a sublayer of skin called the dermis, which is filled with blood vessels and nerve endings (which is why they bleed and hurt). Each poke of the needle evokes a response from your immune system, because technically each poke is a wound that needs healing.

Your macrophages come rushing to help. They’re part of your immune system that helps flight inflammation, and it’s their job to soak up all that ink in their bellies (we know, we know, that’s a very simplified description). Along with fibroblasts, the macrophages help absorb the ink, which changes their normal coloring. They then stay suspended in your epidermis (hopefully for a long time)!